1. Field of the Invention
The present invention relates to a method of warming-up an electrophotography image forming apparatus. More particularly, the present invention relates to a method of warming-up an electrophotography image forming apparatus, capable of enhancing a performance efficiency of a pressing roller within a short time by driving an image fix-related driving body built in the electrophotography image forming apparatus immediately after a wake-up event is generated or when power is turned on, thereby securing a warming-up temperature of the pressing roller in advance.
2. Description of the Related Art
An electrophotography technique is often used in image forming apparatuses such as laser beam printers, copiers, or plain paper fax machines.
FIG. 1 illustrates a conventional image forming apparatus 10 employing a related art electrophotography. As shown in FIG. 1, the image forming apparatus 10 includes a charged roller 11 for printing an image data on a print paper, an organic photo conductive (OPC) drum 12, an exposing device 13, a developing roller 14, a transfer roller 15, a pick up roller 16, and a fixer 18. In an exemplary print process, a high voltage is provided to the charged roller 11. The charged roller 11 rotates and charges a photosensitive body applied to a peripheral surface of the OPC drum 12. Then a light generated by the exposing device 13 forms on the surface of the charged OPC drum 12 and forms an electrostatic latent image for printing. Later, a toner supplied from the developing roller 14 is applied to the electrostatic latent image formed on the surface of the OPC drum 12, and forms a visualized image. The high-voltage transfer roller 15 transfers the visualized image formed on a transported print paper 17. The visualized image being transferred to the print paper 17 is affixed onto the print paper 17 under high heat and high pressure from a heated roller 19 and a pressing roller 20 that are built in the fixer 18.
Usually, the image forming apparatus 10 operates in one of the following four modes: a printing mode, a ready mode, a power-saving mode, and a warming-up mode. To maintain and advance these modes, more than one driving body is required to be inside the image forming apparatus 10. Another related driving body is also set to work when the image forming apparatus 10 is turned on or changes from the power-saving mode to the warming-up mode when the wake-up event is generated. In other words, the image forming apparatus 10 has two driving bodies. One is a main driving body that is related to rotation of the OPC drum 12, and the other is an image fix-related driving body that is related to an image fixing process. According to a related art algorithm, when the heated roller 19 reaches a warming-up starting temperature after power-on or generation of the wake-up event, the main driving body connected to the OPC drum 12 and the image fix-related driving body connected to the fixer 18 are, respectively, set to drive for the warming-up, to raise temperature of the heated roller 18 up to a warming-up objective temperature. There are differences in these two driving bodies in terms of driving objectives. Through the main driving body's action, the OPC drum 12 is evenly charged by the high voltage provided by the charged roller 11, and through the image fix-related driving body's action, the heated roller 19 and the pressing roller 20 are, respectively, rotated and warmed up to an appropriate temperature for fixing an image. Because the OPC drum 12 has a short lifespan and is very expensive, it is set to rotate only for a predetermined time in order to prevent any damages from frequent rotations. However, in case of the related art image forming apparatus, temperature transition of the pressing roller 20 is disregarded, and thus both driving bodies are designed to drive together at the same point. That is, the main driving body and the image fix-related driving body start driving together following power-on or generation of the wake-up event, or from a certain warming-up starting point. This is because the same algorithm applied to an image forming apparatus having one single driving body is applied to the image forming apparatus having the main driving body and the image fix-related driving body, and also because the main driving body is driven only for a predetermined time to reduce damage in the OPC drum 12. However, it is not necessary that the main driving body and the image fix-related body always drive together. Moreover, a heat source built in the heated roller 19 starts driving from the warming-up starting point. As the heat source drives and the pressing roller 20 and the heated roller 19 rotate, temperature of the heated roller and the pressing roller 20 reaches an objective temperature, respectively. More specifically, the heated roller 19 is heated directly by the heat source therein while the pressing roller 20 is heated using an indirect method. In other words heat is transferred from the heated roller 19 as the pressing roller 20 is in contact with the heated roller 19. The heated roller 19 is heated more than the pressing roller 20 because the heated roller 19 has its own source for raising temperature. Therefore, the pressing roller 20, which is heated indirectly, takes a relatively longer time to get to its objective temperature. Accordingly, even after the heat source is turned off because the heated roller 19 reached the warming-up objective temperature, there needs to be a predetermined time for heat transfer from the heated roller 19 to the pressing roller 20. In fact, this is a major factor that determines standby time for the warming-up period. As discussed above, the conventional warming-up method requires a long period of time to transfer heat from the heated roller 19 to the pressing roller 20, thereby consuming more time for the warming-up, which indicates that a user has to wait longer before using the image forming apparatus. Therefore, an improved warming-up method is required to solve the above-mentioned problem.